Introduction
The Accu2 is build around two 18650 Li-Ion batteries. When they wear with time and the lighning timiing becomes too short, it's time to replace the batteries to get a new working Accu2.
Beware, the conception is very XXIth century compliant : you're not invited to get in. Despite this, with some patience and versatility you'll get it done.
Finally some advisory foreword : you're going to manipulate a device with powerful Li-Ion batteries inside which are not or very few limitated in current intensity. This means that in case of a short, you may drain up to 30 A from on battery cell ! Enough to hurt you badly, be cautious!
Warning: Batteries can be dangerous. Exercise extreme caution when following this guide.
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The top is maintained by four slotted screws... with a nice central tip !
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To unscrew them, get an old slotted screwdriver in which you'll make a slot in the center of the blade (see picture 2).
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Open the lid carefully, taking care not to damage the seal.
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You can heat the cover a little with a hairdryer to soften the adhesive of the foam pads located between the motherboard inside the cover.
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Unsolder the four connections of the batteries wires, marked C1+, C1-, C2+ and C2- on the board.
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Be aware that they are soldered with a great amount of tin, you'll have to remove a good quantity of it. Beware not to heat too much the components around risking to unsolder them !
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The P+ and P- wires aren't to be unsoldered. You can do this if you want though.
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Lift up gently the main board from the opposite side of the wires to gain access to the two hax 6mm bolts that maintain the wires.
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Using a hexagonal socket unscrew the two nuts. Be careful to recover the two split washers
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The body is maintained in the housing by the two wires that connect to the lamp.
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You'll have to unscrew them. Get the hex socket with its square only partially fitted in, so that the socket is long enough to unscrew.
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Dont't unscrew totally, begin with only 4 to 5 millimeters (see picture 2)
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Heat the bottom of the housing to soften the glue which is at the bottom of the batteries. You may use an hairdryer for 3 to five minutes to achieve that.
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Now you can push on the wires, and pull on the bolts that you can have screwed back a little bit.
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Take off gently the connecting strips along the batteries. You'll have to use some force to dismantle the electric soldering at the batteries ends. Try to keep the maximum length of the strings in order to facilitate the remounting process.
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Mark the routing of the strings and the polarity of the batteries on the body (one with the + on top on on the bottom)
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You can notice a small white box in the middle of the strings. It's a thermal protection with a switch inside that wxill open above 75°C.
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On the way back, prepare your new batteries in soldering the wires on them (mind the position on the batteries). Get the thermal paste back in place to ensure good contact.
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To reassemble follow the instructions in reverse order
- To rebuild the welding strip connection to the batteries, the best is electrical soldering. If you can only iron solder, be really careful not to heat the battery for a too long time.
- When inserting the batteries block into the housing, make sur it fits well and the connection strings and the thermal switch fit well and do not block.
- Before closing the top, make sure all the protection foams are in place and that the gasket is clean. Finally tighten the screw without exagaration, remember the force you applied unscrewing them.
To reassemble follow the instructions in reverse order
- To rebuild the welding strip connection to the batteries, the best is electrical soldering. If you can only iron solder, be really careful not to heat the battery for a too long time.
- When inserting the batteries block into the housing, make sur it fits well and the connection strings and the thermal switch fit well and do not block.
- Before closing the top, make sure all the protection foams are in place and that the gasket is clean. Finally tighten the screw without exagaration, remember the force you applied unscrewing them.
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9 Comments
Could you do mine……. How much.
Hello, I possibly could, but I live in the south east of France… If you have to add the shipping costs it’s not a bargain and you’d better try it :-)
Otherwise if we can meet I would happily help you !
pichel -
Do you have the voltage and amperage of the charger? I'm planning to cut the wire in the side and add a IP68 connection to it (like a Bypass). So it'll be possible to connect another charger with the same properties, without destroying the proprietary connection.
Hello,
I've looked on the original charger, it says 8,4 V and 1A. 8,4 V is relevant for two Li batteries in serial, 1A is what the BMS needs for charging. If you can find a greater powered charger it's not a problem : the BMS will only takes what it needs and if your charger can deliver less than 1A it will still work, but in a greater timeframe though.
Is it possible to replace these cells by two Nitecore 3500 mAh?
Do you have an email, i have some questions and would like to understand?
Hi, the replacement cells must be able to deliver up to 30 A. Maybe 20A would do, but I tried 14A cells and that won't work well. So I sticked to the original capabilities of the genuine cells and finally there aren't many choices, you will very often come back to the original :
Sony / Murata US18650VTC6 3000mAh - 30A
I've quickly checked among the Nitecore cells, and I found one that might do the job : Nitecore IMR 18650 - 3100mAh 3.7V 35A Li-ion
When cells are able to deliver more than 10A it's usually written on it or its technical specs, if it's not stated, look further : you wont have enough drain current.
Bonjour, je tombe cet interressant tutoriel alors que j'ai presque "terminé " le remplacement de mes cellules, mais j'ai un problème avec le BMS: les 4 leds restent allumées en permanence sauf lorsque j'appuie sur le bouton test (soit l'inverse de ce à quoi on devrait s'attendre...) j'ai surement endommagé un ou plusieurs CMS sur la carte en chauffant peut-être un peu trop pour nettoyer les trous de soudure des accus... auriez vous par hasard un schéma de cette carte ou a défaut les références des composants se trouvant à proximité des connexions que l'on doit dessouder pour remplacer les batteries?
Merci pour votre aide
Bonjour Stéphane, je ne dispose pas de schéma de la carte, et je n'ai pu trouver d'info chez Petzl en grande partie parce que ce n'est pas eux qui la fabriquent. C'est dommage de de pouvoir en retrouver car cela permettrait de réparer à moindre gaspillage pratiquement tous les Accus2 et 4 !
J'ai aussi une paire de BMS à la maison dont les leds de test restent allumées, ou toujours éteintes, mais que je n'ai jamais réussi à diagnostiquer. Autant c'est le contrôleur dont le programme a pris une châtaigne et qu'il "suffirait" de pouvoir flasher pour que tout rentre dans l'ordre. Mais faute d'infos on ne sait pas faire. La plupart des petits CMS autour du contrôleur de charge sont des petits condensateurs que tu peux tester. Je cherche la référence du contrôleur car j'avais trouvé un schéma de montage de base, très proche de ce qui a été fait sur la carte par Petzl.
